Thread 2940318

how do you cast(is that correct?) toys, to reproduce it? i guess using silicone is recommended but how do you then make holes to pour, holes to run it between parts... and then to assure the runners snap easily?

You can also use resin. I recommend you watch the videos made by that silent gen boomer.

>>2940334
lol, which resin do you recommend

>>2940340
This one looks good why not
https://a.aliexpress.com/_oodTq3z

>>2940378
ok, thats noted. how about pouring runners? making holes to pour and such

>>2940388
Usually the air vent is a tube at the top but theres more to it do i still recommend you watch dome youtube tutorials.

>>2940428
which tutorial

>>2940644
Look up robert tolone on youtube

>>2940649
oh ok. which one tho. its massive. kinda

I'll piggyback off this thread. Couple years ago I used a cloning kit to make a silicone toy for the missus. She complained the silicone was too hard, so I made a second one using alginate and Smooth-On Dragonskin 10NV.

She now wants a new one, identical but with for dots and ribs etc. for more texture. How do I modify the last one and make a new one from it? Should I make a mold from it, cast it in plaster or wax, sculpt onto it new details, and then re-cast it in silicone? What materials or techniques should I use? (sculpting in plaster isn't fun)

BTW I didn't degass it last time bc I thought the NV would prevent bubbles (it didn't). One complication I have now is that the NV apparently inhibits curing in other platinum-cured silicone, and I'm not sure I want to use this exact brand again. Also vacuum pumps are fucking expensive apparently.

>>2942440
Bump. OP is a fag but I could really use some actual advice.

>>2943361
Bumping again.

>>2942440
What was the original mold made from? Cast a new dildo one using a firmer material that won't fuck up that mold (stick to it, expand and destroy it, etc.). Then add details to your new dildo. Either find something that can stick to it, drill holes and add wire to mold clay onto it, that kind of thing. Finally, make a new mold off of your modified dildo. You can now cast a new dildo with that mold.

>>2940318 (OP)
>how do you cast(is that correct?) toys, to reproduce it?
You make a master. You apply mold release to the master. You suspend it in a cask to pour the first half of the master mold, hopefully with some indexing features, a pour spout, and a vent. You then apply mold release to the first half of the cured mold.
Then you pour and cure the second half of the mold or use a cover plate if the topside of the part is flat.

The laziest method is to suspend the master into a container with string, and a large rubber cord for the pour line. Pour and cure the mold, then use a knife to intentionally jaggedly cut the master mold in half.

Different resin systems for casting are going to require different processes and equipment. I mostly did pressure-casting to eliminate bubbles and shorten cure times.

The process and requirements for casting hollow PVC parts is very different and requires electroplating and roto-molding. There are a lot of videos on these topics available.

>>2942440
If you still have the original mold just cast a sculpting dummy master you can modify as desired.
If not, just use the original master or copy, use it to make a dummy mold out of paper mache and syran wrap, then cast a new master out of something fast that you can sand or add to with plasticene or modeling clay. Silicone moldmaking 2-part systems don't heat up enough while curing to soften modeling clay.

>>2943922
cont'd
Here are some multi-part molds I made for more complex parts. I used metal rods, silicone tubing, backing plates, and master parts to pour the mold.

The metal rods would get lightly oiled, rubber tubing slid over them, then put into the molds. After the resin cures, you can pull the metal rods out of the silicone tubing, then the silicone tubing can be stretched until it releases from and escapes the inside of the cast part. This provided pilot holes (or even finished hole sizes) in the cast parts.

>>2943926
Second photo showing casting process.

>>2943927
For parts with large flat sides, you can just lightly glue them to a base plate. Then pour the mold. Pour spouts and vents aren't required in this circumstance because you can overpour the cavities, then just top the mold with a polypropylene sheet. Or you can use a hobby knife to cut pour spouts and vents into the mold after it is cured.
I later got rid of the spouts and vents and just did overfill casting because I could fill a mold, cover it with a propylene sheet, stack another mold on-top of it, fill that one, cap it with another sheet, and repeat until I had a whole stacked wedding cake of molds to transfer into the pressure pot. As shown in
>>2943922

>>2943903
>What was the original mold made from?
Me. I used medical alginate to get a negative, a process I don't care to repeat, then I cast the silicone into it.
>>2943923
The original mold is gone (alginate doesn't last that long even in the fridge). I'll have to either create a new mold or sculpt somehow directly on the item for re-casting.

Can I sculpt onto silicone somehow? ChatGPT recommended coating the item in Elmer's glue or similar sealant, so it's completely non-reactive with any new silicone, then decorate it with polymer clay (if it even stick to it, which I doubt). I could then create a new mold using rubber silicone and cast that again.

>>2944034
Also, I decided to buy a vacuum pump and chamber, and not bother with the Dragonskin 10NV. I need recommendations for another platinum-cured silicone with appropriate hardness, and also a rubber I could use for a mold to cast it into that is non-reactive, although I doubt anyone here has much experience with it.

>>2944034
>Can I sculpt onto silicone somehow?
modeling clay will adhere well enough for casting a new master. Getting anything glued to silicone is pretty annoying because the few glues that do work are not as pliable/flexible as silicone itself and eventually separate. But you do only need things to hold long enough for a mold to cast around it.
>>2944035
>Also, I decided to buy a vacuum pump and chamber
I never had good results using vacuum. But then again the resins I worked with had relatively short cure times so vacuum was eating up time that I needed to set the molds properly. If you want to reduce bubbles get a compatible system thinner (especially with clear resin systems) use pressure casting for curing it, and be really careful not to introduce air while pouring. You get more consistent results.
Vacuum was only ever useful for pouring the molds themselves. But the reason to use it for that is to lengthen the usable life of the mold in pressure casting or vacuum casting as repeated inflation/collapse of the bubbles will ruin mold over time. If you don't intend to ever pressure cast with clear resins having air bubbles in your mold isn't an issue.

Pressure casting is good for collapsing bubbles. Vacuum is useful for trying to solve localized flow and infiltration issues in confined spaces.

I mostly used Smooth-On SmootSil blue for moldmaking in order to cast urethane. To do the inverse you will probably want to use Urethane rubber for the molds.

>>2940318 (OP)
>>2940388
>how do you then make holes to pour, holes to run it between parts... and then to assure the runners snap easily?
speaking from a jeweler's background if you're duplicating an item you need to attach things to the item that will create the holes and runners you will need. in jewelery the simplest one is a short length of rod with a cone on one end. you attach that to the piece, align everything so the fat end of the cone is at the end of the mold, and when you make the mold it will now have a little funnel and a channel for the wax to go into. from there the wax copies are connected by their little sprues to a larger wax sprue, then the whole thing is used to make the mold for metal pouring. this is called lost wax casting if you want more specifics. as far as to go, plastic ones are generally injection molded, not cast and I don't think that would work well at home.

>>2944200
Specifically for this kind of toy I was told vacuum is 100% necessary to avoid porous surfaces for bacteria to grow in. I also read for this silicone pressure chambers aren't good enough because it's too viscous. My main issue is this shit be expensive and I'm only ever casting one thing; it's not like buying a good drill, that you'll surely use again.

You suggest sculpting directly on the silicone cast? I can't see how the sculpy will hold; is the elmer's glue plan worthwhile at all?

I thought of making a mold in cheap material like plaster, casting something like wax or oil-based clay inside (last one's risky with platinum-cured silicone I think), modifying that and making a mold from that, any concerns here?

>>2944279
>I can't see how the sculpy will hold
I'm not talking about sculpy, I'm talking about modeling clay like plasticine.

Yes. If your mold-making material is cheap then it's advisable to just make an initial mold with the original and use the interim mold to cast a new master in a material that would be much easier to sculpt more details and features onto, as well as being able to sand the new master to get the surface finish you want on the final part. I'm fond of butyrate systems, but urethane is just as suitable. Polyester and Acrylic systems are common for making miniatures, but I'm not fond of their material properties and propensity to warp while curing.

Then make the final mold out of a more durable material that will transfer the surface finish more effectively.

>>2944347
>modeling clay like plasticine
doesn't plasticine often cause cure inhibition in platinum-cured silicone?
>make an initial mold with the original and use the interim mold to cast a new master in a material
What would you suggest as mold material for the initial silicone toy? Simple plaster will lose a lot of the fine details, and will likely also require to be a two-part mold so I could take the cast out of it, if it's not made of very soft silicon.

>>2944496
>doesn't plasticine often cause cure inhibition in platinum-cured silicone?
Not in my experience. I used it to seal seams in molds and fill in rough surfaces of 3D printed parts. You're probably going to use an interim mold anyway. Plasticine would only be a big issue if your entire master were made from it, in which case you would be limited to making the mold from polysulfide rubber. Alot of the heavier and more clay-rich modeling clays like the ones used in automotive design and sculpture have high sulfur content.

Silicone is very incompatible with buna-n rubber, epdm rubber, and some nitrile products. I tried to use silicone to make a duplication mold of some wiper and cup seals and the silicone never cured against the rubber.
>>2944496
>What would you suggest as mold material for the initial silicone toy?
You can use a cheaper silicone product like RTV or epoxy putty. Or something cheaper by volume like urethane rubber or alginate again. It doesn't have to be a high quality reusable mold or even more than a single-use mold unless you have some concerns about your capability to sculpt or add features to the resulting part.
And for your final mold unless you are intending to make 50 duplicates higher quality grades of silicone probably aren't needed either.